Global warming has already harmed the world’s food production and has driven up food prices by as much as 20% over recent decades, new research has revealed.

An Indian farmer displays wheat after harvest on the outskirts of Jammu, India, Thursday, May 5, 2011. Global warming has already harmed the world’s food production and has driven up food prices by as much as 20% over recent decades, new research has revealed. (AP Photo/Channi Anand) The drop in the productivity of crop plants around the world was not caused by changes in rainfall but was because higher temperatures can cause dehydration, prevent pollination and lead to slowed photosynthesis.

Lester Brown, president of the Earth Policy Institute, Washington DC, said the findings indicate a turning point: “Agriculture as it exists today evolved over 11,000 years of reasonably stable climate, but that climate system is no more.” Adaptation is difficult because our knowledge of the future is not strong enough to drive new investments, he said, “so we just keep going, hoping for the best.”

“It is vital,” said Wolfram Schlenker, at Columbia University in New York and one of the research team. “If we continue to have the same seed varieties and temperatures continue to rise, then food prices will rise further. [Addressing] that is the big question.”

“We actually have enough calories to feed the world quite comfortably, the problem is meat is really inefficient,” as many kilogrammes of grain are needed to produce one kilogramme of meat, he said. “As countries get richer and have a preference for meat, which is more expensive, they price people in poorer countries out of the market.”

Global food prices have risen by about 200% in recent years, says Schlenker. Other causes of the rise are the increased demand for meat and the diversion of food into biofuels. Nonetheless, the researchers conclude that the negative impact on crops overall is “likely to be incurring large economic and health costs”.